Tast buds

Taste buds
Taste buds are present on fungiform, foliate, and circumvallate papillae. In histologic sections, taste buds appear as oval, pale-staining bodies that extend through the thickness of the epithelium .A small opening onto the epithelial surface at the apex of the taste bud is called the taste pore. Three principal cell types are found in taste buds:
• Neuroepithelial (sensory) cells gustatory (taste) cells, are the most numerous cells in the taste bud. These elongated cells extend from the basal lamina of the epithelium to the taste pore, through which the tapered apical surface of each cell extends microvilli. At their base they form a synapse with the processes of afferent sensory neurons. The turnover time of neuroepithelial cells is about 7-10 days.
• Supporting cells are less numerous. They are also elongated cells that extend from the basal lamina to the taste pore. Like neuroepithelial cells, they contain microvilli on their apical surface and possess tight junctions, but they do not synapse with the nerve cells. The turnover time of supporting cells is also about 10 days.
• Basal cells(stem cells) are small cells located in the basal portion of the taste bud, near the basal lamina. They are the stem cells for the two other cell types, these cells have ability to division and differentiation to another type of cells(Fig,3).
Function.
Taste buds detect at least five broad categories of tastants: sodium ions (salty); hydrogen ions from acids (sour); sugars and related compounds (sweet); alkaloids and certain toxins (bitter); and amino acids such as glutamate and aspartate (umami; Jap. umami, savory). Salt and sour tastes are produced by ion channels and the other three taste categories are mediated by G-protein–coupled receptors. Receptor binding produces depolarization of the gustatory cells, stimulating the sensory nerve fibers that send information to the brain for processing. Conscious perception of tastes in food requires olfactory and other sensations in addition to taste bud activity.
In Glands of von Ebner are minor salivary glands that deliver their serous secretion into the furrow surrounding each papilla, assisting the
Dr.Hameda abdulmahdi College of Medicine /Dep. of anatomy histology
2nd stage
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taste buds in perceiving stimuli. These glands also deliver their saliva into the furrows of the foliate papillae.
? The muscular core of the tongue is composed of bundles of skeletal muscle fibers arranged in three planes with minor salivary glands interspersed among them. Connective tissue between the small fascicles of muscle is penetrated by the lamina propria, which makes the mucous membrane strongly adherent to the muscular core.
1. A lingual tonsil is located on the dorsal surface of the posterior one-third of the tongue.
(Figure